Disperse dyeing of cellulose triacetate



United States Patent 3,135,576 DISPERSE DYEING 0F CELLULGSE TRKACETA'IE Colin L. Browne and William J. Myles, Charlotte, N.C., assignors to Celanese Corporation of America, New York, N.Y., a corporation of Delaware No Drawing. Filed Oct. 17, 1960, Ser. No. 62,887 11 Claims. (Cl. 8-57) The present invention relates to the dyeing of cellulose triacetate filamentary materials.

Cellulose triacetate filamentary materials are relatively slow dyeing as compared with conventional acetone-soluble secondary cellulose acetate. Moreover, when dyeing cellulose triacetate with disperse acetate dyes, the dyeings are not always level and washfast. If other fibers are present they will often be stained by the disperse acetate dye.

It is accordingly an object of the present invention to provide an improved process for dyeing cellulose triacetate.

Another object of the invention is to provide improved dyeings of cellulose triacetate alone and/or in blends.

Other objects and advantages of the invention will become apparent from the following detailed description and claims wherein all parts are by weight unless otherwise specified and wherein all acetyl values are calculated as combined acetic acid by weight.

In accordance with one aspect of the present invention cellulose triacetate filamentary material is dyed in a dispersion of a disperse acetate dye in an aqueous liquor or dyebath having dissolved therein the acetic acid ester of triethyl citrate or fl-butoxyethanol, i.e., acetyl triethyl citrate and ,B-butoxyethyl acetate. These esters are of low water solubility and are present in the dyebath in about 0.25 to 10% on the weight of the dyebath. If more ester is used than can be dissolved in the bath the excess will be dispersed and will be cleared when the fiber extracts the ester from the dyebath. For fl-butoxyethyl acetate the preferred concentration is about 0.5 to by weight of the dyebath and for acetyl triethyl citrate about 0.25 to 5%. For reasons of economy, quality of results and efiectiveness at low concentration acetyl triethyl citrate is preferred.

The acetic acid esters employed" in the indicated amounts elfect increases in the rate and depth of dyeing, permitting desired shades to be obtained with only a fraction as much dye as is otherwise required and sometimes permitting deep shades to be obtained which cannot be obtained regardless of how much carrier is employed. In addition, the use of these esters effects. an improvement in washfastness and hand, in strength retention following heat treatment and in safe ironing temperature. Finally, the esters permit knit fabrics such as tricot to be winch dyed without warp streaks which eliminates the need for more costly pressure equipment and very high temperatures. Filling bands are eliminated in woven fabrics having a cellulose triacetate filling and a warp of another fiber.

Dyeing may be carried out at temperatures in excess of about 50 C. up to temperatures beyond which the filamentary material is damaged and preferably is carried out at temperatures ranging from about 60 to 95 C. It may be carried out in pressure equipment, if desired, but

as noted it can also be carried out on the winch or jig. Liquor ratios of 2:1 to :1 or more may be used although they preferably range from about 3:1 to 8:1 for jig dyeing and from about 20:1 to 50:1 for winch dyeing. Since the liquor ratio will govern the proportion of acetic acid ester to fiber at any given concentration of the ester, it is apparent that the optimum concentration will to some extent be related to the liquor ratio. Thus, at the preferred liquor ratios the preferred acetic acid ester, acetyl triethyl citrate is preferably used in a concentration of about 0.3 to 0.5% when dyeing on the winch and about 1 to 2% when dyeing on the jig. This corresponds to a range of about 3 to 25% of acetyl triethyl citrate based on the weight of fiber. At the preferred liquor ratios the fl-butoxyethyl acetate is preferably used in a concentration of about 0.5 to 1% on the winch and about 2 to 4% on the jig, corresponding to about 6 to 25% on the weight of fiber.

The process is especially suited for dyeing with disperse acetate dyes such as Disperse Blue 27, Disperse Red 35, Disperse Yellow 37, and the like, although other classes of dyes such as basic dyes can be employed with somewhat lesser success.

As employed herein cellulose triacetate has reference to cellulose acetate having an acetyl value of at least about 59% and preferably at least about 61%, i.e. at most about 0.29 free hydroxyl group and preferably at most about 0.12 free hydroxyl group per anhydroglucose unit of the cellulose molecule.

The cellulose triacetate textile filamentary material may be in the form of staple fibers, tow, continuous filament or staple fiber yarns, fabrics and/or finished articles. They may be alone or in admixture with other fibrous materials such as wool, cotton, rayon, silk, nylon, glass, polymers and/0r copolymers of vinylidene compounds such as acrylonitrile, ethylene, propylene, vinyl chloride, vinyl acetate, vinylidene cyanide, and the like. It is an advantage of the present invention that when dyeing a blend the blend fiber is not stained with the disperse acetate dye. If a mixture of dyes is employed, e.g. if a cellulose triacetate-Wool blend is dyed with a bath containing one of the disclosed acetic acid esters along with a disperse acetate dye and an acid dye the cellulose triacetate will not be stained by the acid dye nor will the wool be stained by the disperse acetate dye.

Following dyeing the filamentary material may be rinsed and/ or scoured in conventional manner to remove loose dye and to wash out the acetic acid ester. If a subsequent heat treatment is desired, notwithstanding the already increased safe ironing temperature, it may be carried out in conventional manner as by raising the temperature of the filamentary material above about C. and preferably above 200 C. for a time sufficient to increase the crystallinity and to improve the washfastness but insuflicient to produce any substantial damage. The heating can be effected by contact as with metal cans or rolls, by hot air as on an enclosed tenter frame or by radiant heat. Alternatively heat treatment can be carried out at somewhat lower temperatures by using steam at superatmospheric pressures.

The following examples further illustrate the invention.

Example I Tricot, knit of cellulose triacetate yarn which was surface saponified in conventional manner to reduce its acetyl value from 61.5 to 60.5%, is dyed on a winch with a bath including 17 times as much water as the weight of fabric, 9.05% of sodium N-methyl-N-oleyl taurate, 0.02% of soda ash, 1% of fl-butoxyethyl acetate, 0.05% of a nonionic alkyl aryl polyether alcohol detergent, 0.05 interchemical Blue GSF (Disperse Blue 27), 0.03% Eastone Red NGLF (Disperse Red 35) and 0.04% of Amacel Yellow CW (Disperse Yellow 37). The bath is heated to 80 C. in 45 minutes and maintained at that temperature for 4 hours. The bath is then cooled to 45 C. in 15 minutes by addition of cold water while still running the fabric. 0.05% of a cation active .agent, sold under the trademark Ceranine HC, is added to the bath and after 15 minutes more the fabric is removed, extracted and dried. The fabric is dyed an even light brown shade with no visible warp streaking. It does not stiffen even upon moderately severe heat treatment and the strength of the heat treated fabric is significantly higher that that of a control treated identically except for omission of the p-butoxyethyl acetate. The last treatment produces a markedly greater change in the shade of the control as contrasted with the product of the example.

Example [I A woven fabric having alternate warp and filling bands of wool ends and cellulose triacetate ends of 61.5% acetyl value and comprising 50/50 wool/ cellulose triacefate is agitated in a bath Weighing 50 times the fabric and containing 1% of B-butoxyethyl acetate, 0.1% of a watersoluble polyethylene ether of a fatty acid sold under the trademark Emulphor, 0.05% of sodium N-methyLN-oleyl taurate, 1.4% on fabric weight of Eastman Blue BGLF (Disperse Blue 27) 1.4% on fabric weight of Eastone Red NGLF (Disperse Red 35) and 0.8% on fabric Weight of Amacel Yellow CW (Disperse Yellow 37). The temperature of the bath is brought up to 80 C. over 30 minutes, the pH then being 5 .5, and dyeing is continued at 80 C. for 1 hour. The fabric is rinsed in cold water and scoured by agitation for minutes in a bath at 55 C. and containing 0.2% of the neutral sodium salt of a complex condensed aryl organic acid sold under the trademark Tamol N and 0.1% of soap. The scouring bath is only lightly colored. The fabric is again rinsed and then dried. The cellulose triacctate is dyed an even brown. The wool is substantially unstained. Staining is so slight that addition of alkali during dyeing to maintain the pH at 8 does not produce any less staining.

A control sample dyed essentially similarly at 95 C. with 0.4% of butyl benzoate in place of the fl-butoxyethyl acetate shows a lighter shade on the cellulose triacetate, considerably more staining on the wool, greater washdown as evidenced by the color of the scouring water, poor lightfastness and weakening of the wool. Higher proportions of butyl benzoate are without additional advantage.

Example III 10 kilograms of chambray fabric having a cotton warp and a filling of cellulose triacetate, 61.5% acetyl value, is loaded on a Winch filled with 4-50 liters of cold water and containing 0.05% of sodium N-methyhN-oleyl taurate. The fabric is wet out. 3.6 kilograms of fi-butoxyethyl acetate are added along with 225 grams of an alkyiarylpolyether alcohol sold under the trademark Triton X-l00. There are also added, based on the weight of fabric, 1% of Eastman Blue BGLF (Disperse Blue 27), 1% of interchemical Yellow HDLF-40 (Disperse Yellow 37) and 0.1% of Eastone Red N-GLF (Disperse Red 35) as disperse dyes for the cellulose triacetate and 0.5% of Superlitefast Blue 16 ELL, 0.4% of Superlitefast Yellow EEC (Pr. 629) and 0.125% of Chlorantine Scarlet BNLL (Direct Red 89) as direct dyes for the cotton. Over 35 minutes the temperature of the bath is raised to 80 C. the front of the winch, resulting in a temperature of about 70 C. at the back. The fabric is run for 45 minutes Example IV The process of Example III is repeated with the following differences: the 3.6 kilograms of fi-butoxyethyl acetate are replaced by 1.35 kilograms of acetyl triethyl citrate, the alkylarylpolyethe'r alcohol is increased to 270 grams and the temperature at the front of the winch is raised to 90 C. There are slightly more filling bands than in Example Ill but far fewer than when dyeing with conventional carriers in the bath.

Example V 10 kilograms of the same fabric as in Example III is dyed on the jig with the same proportion of dyes as follows: the jig is filled with 125 liters of cold water and the fabric is wet. 1875 grams of acetyl triethyl citrate and 625 grams of an alkylarylpolyether alcohol are added over two passes of fabric through the bath and the fabric is run through twice more. The same dyes as in Example III are added in the same proportions over two passes of the fabric through the jig. After two more cold passes, the, temperature is raised to 95 C. over 35 minutes and maintained by steam injection. The fabric is passed through the bath for an hour, 5000 grams of sodium chloride are added and dyeing continued for 2 /2 hours. The bath is dropped, the jig filled to overflowing with water at C. and the fabric rinsed while allowing the temperature to drop. The fabric is treated with Sandofix WE, a cationic fixative, by exhaustion from a bath at C. containing 0.5 on fabric weight, extracted and dried. The fabric is a very level almond color substantially free of filling bands. The use of acetyl triethyl citrate as contrasted with dyeing in its absence permits a desired depth of shade to be attained with far less dye, minimizes the problem of filling bands and eliminates staining of the cotton with the disperse dyes as can best be observed by omission of any direct dye for the cotton.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention what we desire to secure by Letters Patent is:

1. The process for dyeing textile material comprising cellulose triacetate which comprises contacting said material at an elevated temperature with an aqueous dyebath containing a disperse acetate dye and an acetic acid ester selected from the group consisting of acetyl triethyl citrate and fi-butoxyethyl acetate present in about 3 to 25% of the weight of the textile material.

2. The process for dyeing textile material comprising cellulose triacetate which comprises contacting said material at an elevated temperature with an aqueous dyebath containing a disperse acetate dye and acetyl triethyl citrate present in about 3 to 25 of the Weight of the textile material.

3. The process set forth in claim 2, wherein said acetyl triethyl citrate is employed in a concentration of about 0.25 to 5% on the weight of said dyebath.

4. The process for dyeing textile material comprising cellulose triacetate which comprises contacting said material at an elevated temperature with an aqueous dyebath containing a disperse acetate dye and fl-butoxyethyl acetate present in about 3 to 25 of the weight of the textile material.

5. The process set forth in claim 4, wherein said [ibutoxyethyl acetate is employed in a concentration of about 0.5 to 5% on the weight of said dyebath.

6. The process set forth in claim 1 including the further step of heat treating said material.

7. The process set forth in claim 6 wherein said material is scoured prior to said heat treatment.

8. The process set forth in claim 1 wherein said textile material is a warp knit fabric.

9. The process set forth in claim 1 wherein said textile material is a woven fabric and said filling consists essentially of cellulose triacetate.

10. The process set forth in claim 1 wherein said textile material comprises a combination of cellulose triacetate filamentary material and at least one other filamentary material.

11. The process set forth in claim 1 wherein said textile material also comprises cellulose and at least one ceilulose dye is also present in said dyebath.

References (Iited in the file of this patent UNITED STATES PATENTS Lyem Oct. 22, 1946 2,843,448 Thummel et al. July 15, 1958 3,016,280 Fortress et a1 Jan. 9, 1962 

1. THE PROCESS OF DYEING TEXTILE MATERIAL COMPRISING CELLULOSE TRIACETATE WHICH COMPRISES CONTACTING SAID MATERIAL AT AN ELEVATED TEMPERATURE WITH AN AQUEOUS DYEBATH CONTAINING A DISPERSE ACETATE DYE AND AN ACETIC ACID ESTER SELECTED FROM THE GROUP CONSISTING OF ACETYLE TRIETHYL CITRATE AND B-BUTOXYLETHYL ACETATE PRESENT IN ABOUT 3 TO 25% OF THE WEIGHT OF THE TEXTILE MATERIAL. 